Conventionally, a well-known prior heating system utilizes heat produced by a vehicle engine when the vehicle is operating or running. The prior art heating system utilizes a number of pipes which connect the heater with the engine and radiator so that the water flowing in the pipes can transmit the heat produced by the engine to the vehicle's heater while cooling down the heated engine at the same time. The prior art heating system, however, has the problem of time delay (about 30 minutes, or one hour in the cold winter) in achieving the proper vehicle heating mode. That is, to supply the required heated air for proper functioning of the vehicle heater, there is a long delay as the engine itself heats up. Specifically, in the case of commuting vehicles which often make several stops and are parked for various lengths of time, the engine is either kept idling to maintain the required engine temperature or the vehicle is shut off requiring the operator to again wait as the engine sufficiently heats up to an operational temperature. The idling of the engine, either to maintain the pre-existing engine temperature or raise the engine temperature to the desired level, lessens the life span of the engine through continuous or added operation. The requirements of such prior art heating systems also cause economic loss due to unnecessary consumption of fuel. Similar problems also exist with respect to vehicles being relied upon for extended periods of travel in that the engine must be kept idling during periods when the engine is being rested. Furthermore, when it is the operator who desires rest, the user of the vehicle is subject to the noise and vibration associated with an idling engine and often finds sound rest unavailable
As a solution to these problems, an auxiliary heating system for vehicles is already known which provides heat to vehicles when the vehicle engine is stopped and the vehicle is parked. However, the above auxiliary heating system employs a boiler which is structured such that the heat produced by burning fuel fails to provide the desired degree of heating due to low heat efficiency. This low heat efficiency causes an increase in the consumption of fuel which often proves to be uneconomical.
Another disadvantage of the prior auxiliary heating systems is that the boiler forming part of the heating system is too heavy and large in size to be installed in the limited space of the vehicle. It is also often difficult to install the prior art auxiliary heating systems thus making it is expensive to install such systems. Accordingly, such systems are applied only to specially designed vehicles which often turns out to be unrealistic from an economic standpoint
Another disadvantage of the prior art auxiliary heating systems is the frequent breakdowns due to misuse and a lack of safety devices. Also, in the worse cases, the lack of sufficient safety devices leaves open the possibility of an explosion or fire which can claim precious human life or cause the loss of property.
These disadvantages have prevented the general public or users from adopting the prior art auxiliary vehicle heating systems.